1. Field of the Invention
The present invention relates to a golf club, and, more particularly, the present invention relates to a golf club head with integrally attached weight members.
2. Description of the Related Art
Golf club heads come in many different forms and makes, such as wood- or metal-type (including drivers and fairway woods), iron-type (including wedge-type club heads), utility- or specialty-type, and putter-type. Each of these styles has a prescribed function and make-up. The present invention primarily relates to hollow golf club heads, such as wood-type and utility-type (generally referred to herein as wood-type golf clubs).
Wood-type type golf club heads generally include a front or striking face, a crown, a sole, and an arcuate skirt including a heel, a toe, and a back. The crown and skirt are sometimes referred to as a “shell.” The front face interfaces with and strikes the golf ball. A plurality of grooves, sometimes referred to as “score lines,” may be provided on the face to assist in imparting spin to the ball. The crown is generally configured to have a particular look to the golfer and to provide structural rigidity for the striking face. The sole of the golf club contacts and interacts with the ground during the swing.
The design and manufacture of wood-type golf clubs requires careful attention to club head construction. Among the many factors that must be considered are material selection, material treatment, structural integrity, and overall geometrical design. Exemplary geometrical design considerations include loft, lie, face angle, horizontal face bulge, vertical face roll, face size, sole curvature, center of gravity, and overall head weight. The interior design of the club head may be tailored to achieve particular characteristics, such as by including hosel or shaft attachment means, perimeter weighting on the face or body of the club head, and fillers within hollow club heads. Club heads typically are formed from stainless steel, aluminum, or titanium, and are cast, stamped as by forming sheet metal with pressure, forged, or formed by a combination of any two or more of these processes. The club heads may be formed from multiple pieces that are welded or otherwise joined together to form a hollow head, as is often the case of club heads designed with inserts, such as sole plates or crown plates. The multi-piece constructions facilitate access to the cavity formed within the club head, thereby permitting the attachment of various other components to the head such as internal weights and the club shaft. The cavity may remain empty, or may be partially or completely filled, such as with foam. An adhesive may be injected into the club head to provide the correct swing weight and to collect and retain any debris that may be in the club head. In addition, due to difficulties in manufacturing one-piece club heads to high dimensional tolerances, the use of multi-piece constructions allows the manufacture of a club head to a tight set of standards.
The distance a golf ball travels after impact with a golf club is dictated by the magnitude and direction of the ball's translational and rotational velocities. Golf ball travel distance is a function of the total kinetic energy imparted to the ball during impact with the club head, neglecting environmental effects. During impact, kinetic energy is transferred from the club and stored as elastic strain energy in the club head and the ball. After impact, the stored elastic energy is transformed back into kinetic energy in the form of translational and rotational velocity of the ball as well as of the club. Since the collision is not perfectly elastic, a portion of the energy is dissipated as heat, club head vibration, and viscoelastic relaxation of the ball. Golf ball landing accuracy also is driven by a number of factors. Some of these can be attributed to club head design. The club head center of gravity (CG) is of primary concern.
The club head CG is the point at which it is perfectly balanced. The momentum generated in the club head during a golf swing and which is transferred to the ball at impact acts through the club head CG. Lowering the club head CG below the impact point imparts an upward trajectory to the momentum vector, which translates to an upward trajectory on the resulting ball flight. Thus, lowering the club head CG allows the golfer to get the ball airborne quickly. This effect is enhanced by moving the CG back away from the club face. Getting the golf ball in the air quickly is beneficial for most golfers, especially for shots from the rough or when using a wood-type club without a tee.
Heel-to-toe positioning of the CG also has an effect on the resulting golf shot. If the CG is biased towards the heel, the club head is easier to turn over to square at impact. This arrangement is beneficial for a golfer that tends to slice the ball or keep the club face open at impact. Similarly, biasing the CG towards the toe is beneficial for a golfer that tends to hook the ball or have a closed club head posture at impact.
Moment of inertia (MOI) is also an important design aspect of golf club heads. Inertia is a property of matter by which a body remains at rest or in uniform motion unless acted upon by some external force. MOI is a measure of the resistance of a body to angular acceleration about a given axis, and is equal to the sum of the products of each element of mass in the body and the square of the element's distance from the axis. Thus, as mass distance from the axis increases, the MOI increases. As the MOI increases, the stability, playability, and forgiveness of the club head increases. Another way of saying this is that as the club head MOI increases, so does its ability to resist club twisting resulting from off-center hits. Moving the CG back away from the face increases the club head MOI. The CG location and MOI can be manipulated using weights.